A recent offhand comment by a park ranger with a degree in geology, Stephanie Carter, at Crater Lake National Park. According to the University of California at Berkeley Museum of Paleontology website, "The Cretaceous is defined as the period between 145.5 and 65.5 million years ago." It is also known as "the last portion of the 'Age of Dinosaurs.'"
Halliburton, one of the world's largest oilfield services companies, indicates on a graph on page 16 of its Basic Petroleum Geology Book, that 27% (which is the largest percentage) of oil and gas deposits orginates in rocks of the Cretaceous Age.
Dr. Michael E. Mann, climate scientist, professor at Pennsylvania State University, was then asked to comment on Stephanie's quote.
His response: "(I) like to use the example of the Cretaceous period to emphasize the unprecedented nature of the experiment that we are undertaking with the Earth. On very long timescales, volcanic emissions of CO2 matter can gradually raise or lower CO2 concentrations. To be more specific, its the difference between volcanic outgassing and natural update (basically chemical weathering) that leads to CO2 changes seen on geological timescales.
It took nature *tens* of millions of years to raise CO2 to levels appreciably higher than they are today, i.e. where we'll be by 2100 under business as usual (e.g. early Cretaceous).
so we're engaged in an experiment where we are doing, on a timescale of 100 years, what it took nature to do on a timescale of 100 million years, i.e. the magnitude of
our impact is a million times greater than nature."
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